1. Field of the Invention
The present invention relates to a receiving system whereby a series of information signals divided into unit information signals, e.g., scanning line signals of a television signal and transmitted by being inserted in another signal, e.g., another television signal during predetermined time intervals (e.g., vertical blanking periods) are received, the unit information signals inserted in a time-division manner are separated from the second signal, the separated unit information signals are successively recorded on an endless type recording device to reconstruct the series of information signals, and these signals are then supplied to a reproducing device, e.g., a cathode ray tube or speaker to reproduce the original series of information signals.
More particularly, the present invention relates to a receiving system by which is received the information signal for each picture frame which is divided into line signals corresponding to the scanning lines in the frame and transmitted by being inserted in another television signal during the vertical blanking periods. The received scanning line signals are separated from the second television signal and are recorded on an endless type recording device, whereby the recorded signals are read out to reproduce the picture frame on an image display apparatus.
2. Description of the Prior Art
Heretofore, it has been known in the art to transmit the facsimile signal for one or several scanning lines by inserting the signal in a television signal during a portion of each vertical blanking period. At a receiving system, the facsimile signals transmitted during the vertical blanking periods are separated from the television signal and are then reproduced on a sheet of paper.
According to the Japanese Standard Television System, the vertical blanking period of a television signal is 1/60 second. To eliminate any deteriorating effects on the synchronizing signal regeneration circuit of a receiver for receiving the television signal, the maximum time interval that can be utilized for the insertion of such information signal during each vertical blanking period is on the order of several horizontal scanning periods. Consequently, a considerable time will be required, if the facsimile signals for one picture frame are transmitted by utilizing the vertical blanking periods. However, since the receiver for the facsimile signals is required only to successively record on a sheet of paper the facsimile signals received during the vertical blanking periods, the facsimile signals transmitted during the vertical blanking periods on a time-division basis can be easily reproduced.
However, when one still picture frame transmitted by being inserted in a television signal during its vertical blanking periods is to be received to reproduce the still picture, if the video signal for about one to five horizontal scanning lines which was inserted in the television signal at intervals of 1/60 second are supplied to an image display apparatus in the order of receiption, it is impossible to reproduce the still picture due to the peristance characteristic of the image display apparatus that last only for a very short period of time.
To obtain a still picture, it is necessary that the video signal for one to five horizontal scanning periods which is transmitted during each vertical blanking period be recorded on an endless type recording device such as a magnetic disc in such a manner that no space is left between the successively transmitted signals or the signals successively transmitted are not allowed to overlap with each other. In other words, generally a magnetic disc is rotated at a constant speed, and the video signal transmitted during each vertical blanking period must be recorded on the magnetic disc rotating at the constant speed in such a manner that no space is left between the signals or the signals are not allowed to overlap with each other. However, no system or apparatus is known in the art whereby signals transmitted during predetermined time intervals are recorded on such a magnetic disc or the like in the manner just described. The signals recorded on the magnetic disc are read out repeatedly to reproduce a still picture on an image display apparatus. In this case, it is essential that interlacing of the odd and even fields be accomplished satisfactorily. In addition, when transmitting the color still picture signals for one frame during the vertical blanking periods, the phase of the chrominance subcarrier must be varied continuously for each horizontal scanning period. However, no receiving system is known in the art which solves all of these deficiencies and in which video signals transmitted during predetermined time intervals are recorded on an endless type magnetic disc, whereby the recorded signals are read out to reproduce a still picture on an image reproducing apparatus.